Self-centering device



July 28, 1942. H. E. WELLS 2,291,518

ySELF-CENTERINGr DEVICE Filed Dec. 20, 1938 2 Sheets-Sheet ly ff v 27 Z5 SMQ/Mw July 28, 1942.` H. E. WELLS SELF-CENTERING DEVICE Filed Dec. 20, 1958 2 sheets-sheet 2 f W M 2 A /K t. f f f IV w f H m MVX? I iiIi.;

Patented July 28. 1942 2,291,518` i Harold E. Wells, Kenmore, N. Y., as'si'gnor, by

-mesne assignments, to The Cleveland Pneu# I matic' Tool Company, Cleveland, Ohio, a cor.-y

poration of Ohio: I

Application December 20, 1938, Serial No. 846,905

2 Claims.

This invention relates generally to airplane construction, and more especially to a means by which the alignment of a caster wheel may be insured.`

Oneof the objectsof my invention is toprovidel adevice, the operationof which will insure proper alignment of a caster wheel so that it may be retracted into a compartment without damage to the wheel or associated parts of the airplane.

Still another object of my invention is topiovide a device, the operation of which will insure the proper alignment of a caster wheel in the direction of travel maintained byan airplane just before the wheel comes into contact with' the ground.

-Afurther object of my invention is t0 providel a self-centering. device of the type described which is so constructed and positioned that its' wheel assembly to which it is attached.

With these and other objects in view, my invention embraces the conceptof providing a means, the operation of whichv will 'insu're the alignment of a caster wheel at any desired an'- gle'.. In practice, my device may be applied to any type of strut upon which is mounted a caster Wheel. The `strut may also be attached to any desired portionof the fuselage of anairplane and may or may not be retractible.

- use will not increase the weight or drag of the f Inorder to illustrate mylinvention, I have 30 a CQnStsvofa boum." tubevth? upper portion/0f. shown the selecentering device in combiliation glgg gglrlli''g lgemTb l'olw with a retrac ible compression eg of e air v cushioning, oleo type which is attached to the glfufhe cylmder s provlded ."th a packmg forward portion of an airplane to assist in landing. The compression leg comprises a fixed cyl- 35 A plston I4 1S provldd Whlh extends through the gland I3 and carries on its outer extremity mder and a slidable and rotatable piston carried a Wheel fork I5 upon which is mounted h 1 partially Within the Cylindl-, The Piston carris is. The piston la is siidabiy mountedavguii 011 lts Prolectlng end a' mgm fork m which s the cylinder 8 in such a manner that it can be mounted the landmg Wheel- The centering de rotated throu h a redeter i d hi h f rm this inventionY is associated 40 -g' p mne are' vice w c 0 S' n Carried within the cylinder 8 and rigidly con- W1th the Cylinder an@ Plston and ls fntnfely en' nected to the upper end of 'the piston I4 is a cam closed Wlthln the Cyllnflelfrthl ehmmatmg any follower' I1. This cam follower is"provided with additional drag 01' POSSlbllltY Qf damage t0 the an annular upper end I8 which is provided with Working parl/S: A150 bemg {intlley automatl? m 45 oil grooves I9. These o'il grooves act as a seal operation. lt insures the pilot of proper allgnto prevent cushioning air from escaping past the ment o f the wheel both in landing and before cam follower II from the air space 20, the size retraction without the neCeSSlty 0f mampulaof which varies with the distance separating the tion. annular upper end I8 from the upper enclosure In the drawings: -50 II. The lower end of the cam follower I'I con- Figure 1 is a fragmental view in side elevation of the fuselage of an airplane showing a swivel-- ing nose wheel in extended and retracted positions.

Figure 2 is a longitudinal, sectional view of 55 lower I1, is a cam the compression leg'lin parts]` being shown in y elevation.

Figure 3 isa view taken along line 3-43 of'iiigure 2, looking in thedirection'of the arrows.

Figure 4 isa view taken along line [4l-'4uy of. Figure' 2; looking in thedirectionof the arrows.

Figure'lis a longitudinal, sectional view vof a portion' of the compressibleleg showing in'sidefv elevation the cooperating parts of the centering device in a displaced position.

In order toillustrate my invention," 1 `have shownin Figure 1 a portion ofthe fuselageof an airplane, generally indicated by the numeral I, which isprovided withia the fuselage forwardof the airfoil pression leg of the air cushioning, oleo type, which is indicated generally by theqnumeral 5. This leg is hinged 6 andconsists of a pivoting nose blyl which is vmounted 'in a cylinder 8.

Attachedto the outer surface of thecylinder 8 is a broken link9 which connects the leg 5 to the retracting device, such as a cylinder II),`

which is mounted Von the fuselage I. 'Ihe operation of the retracting device-"I0 willcause the extension or retraction by dotted lines.

As bestshown'in Figuresf2` and 3, the cylinderA sists of a wedge-shaped depending portion 2| which is cut away as at 22 in order to reduce weight.

Mounted in the cylinder 8,*below the cam fol- 23 which is provided with a y propeller i2, a landin'g' wheel 3 and a main airfoil 4. Attachedto is a com`v to the fuselage as'shown4 at wheel assem' ofthe leg '5 Vasindicated` cam surface 24, the shape of which corresponds to that of the ycam follower surface 2|. Thisv shown at 26. This anged portion is providedI with-key seats 21 in-which are adapted to lfit keys 28 which are in turn keyed into the interior of the cylinder 8. This construction prevents movement or rotation ofthe cam 23;

In operation, when the 'piston `I4 is relieved of its working load, as, for example, when the airplane leaves the ground, air pressure within the air space 2.0 and the weight of the wheel I6 force the piston I4 downward, thereby causing the cam follower I1 which is attached to the piston Il to move downwardly from its static position shown at 29 in Figure 3.

As best shown in Figure 5, this movement of the cam follower IIbrings its surface 2| in contact with the similarly shaped surface 2l of the cam 23. 'I'he continued downward .movement of thev cam `follower I1 forces the surface 2l to follow thev cam surface 24 until the two surfaces completely coincide inthe maximum extended position of the pistonfll as shown at30 in Figure 3.

In assuming this position, the `carri follower I l, in addition to its longitudinal movement, has been forced to rotate on its ownaxis, thereby rotating the piston Il and the wheel fork l5 which results in proper alignment offthe wheel I6, such as in a. direction similar to that taken by the airplane.

' The leg may now be retracted 'within thefuselage without danger of misalignment of the wheel causing damage to the wheel or fuselage. lThis strut, there is little increase in weight and no increase in drag as would be the case if an external spring or other device were used for the same purpose. v

While for purposes of illustration I have disclosed one method by which my alignment device may be applied for aligning a wheel,A it is obvious that this device can be' used in any construction whereby one part is longitudinally movable in relation to the other. It is therefore apparent that I do not intend my invention to be in any way limited bythe disclosure, and I wish the scope of this invention to be only limited by the prior art and the breadth of the appended claims.

I claim:

1. A landing gear for aircraft comprising, the combination of a cylinder, a piston slidably and rotatably mounted within the cylinder, a wheel position will be maintained until the wheel is V 4 again extended and the leg is compressed upon the wheel coming in contact with theground when it is free to swivel for proper manipulation of the airplane in taxiing.

It is believed obvious from the above description thatI have provided a device which willinsure perfect alignment of a caster wheel so that itmay be retracted into a compartment and also means whereby a. wheel may be aligned with the direction of travel just before the wheel comes into contact with the ground. Asthis device is an integral part of and contained within the aero supported at the lower extremity of said piston, an annular `cam follower rigidly mounted-on the upper extremity of said piston, saidcam follower being provided with a downwardly depending laterally hollow portion having a curved surface, a cam within the cylinder, said cam being rigidly attached vto the cylinder at'a point below the cam follower and being provided with an upstanding member having a `surfacewhich is curved in a manner similar to that of said cam follower, and meansto 'force the piston downwardly in the cylinderV so that the two surfaces will `engage each other', thereby ,causing a partial rotation of the piston and the wheel to which it is attached.

2. A landing gear for aircraft comprising, the combination of a cylinder, apiston slidablyxand rotatably mounted within the cylinder, a wheel supported at the lower 'extremity of said piston, an annular cam follower rigidly mounted lon the upper extremity of said piston, said cam follower beingv provided` with a .downwardly "depending portion having a curved surface, a Vcam within the-cylinder', vsaid cam being'rigidily attached'to thecylinder at' a point below the caniv follower and vbeing 'provided with an upstanding laterally hollow member having a surface which is curved in a manner similar to that' of said cam follower, and meansto forcethe piston downwardly in the cylinderso that the two surfaces will engage each other, thereby causing a partialr rotation of the which 'it is attached.

piston and the wheel to HAROLDVEWELLS. 

